The Sumatra-Andaman earthquake struck in the Indian Ocean on December 26, 2004 and generated a tsunami that wreaked havoc in coastal areas in the region. Worldwide, casualties are estimated to be over 250,000, mostly in Indonesia, the focus of this project. We have three main goals. First, the immediate, medium-term and longer-term consequences of the disaster on mortality, family disruption and relocation, physical and mental health as well as economic and social security at the individual, family and community level will be carefully documented. Second, the project will trace the reconstruction of lives and livelihoods in the aftermath of the disaster, paying attention to the effects of different behaviors in response to the disaster, the roles of kinship and social networks, levels of economic resources, and receipt and leveraging of external aid. Third, we will identify the characteristics and behaviors of individuals, households and communities that are associated with mitigating the negative consequences of the disaster. Special attention will be paid to the impact of death of family members. The evidence will contribute to the scientific literature on the effects of unanticipated shocks on population well-being. To fulfill these goals, we will design, field and analyze data from a multi-wave longitudinal survey of almost 50,000 individuals in tsunami-affected areas of Sumatra and nearby areas. Baseline data were collected in February 2004, prior to the earthquake. The first re-survey is currently in the field. We will conduct four additional annual follow-up surveys to measure the longer term consequences of the disaster, the evolution of rehabilitation and recovery, and identify those who are most vulnerable to longer-term negative consequences of natural disasters. The data will be placed in the public domain arid will be an important scientific resource for better understanding the impact of a natural disaster on population well- being. This project will provide estimates of consequences of the December 26, 2004 tsunami for health, mortality, and other social and economic outcomes. We will identify the characteristics of the individuals who were hardest hit and trace the process of recovery from the tsunami over five years, identifying those individuals and communities that recovered most quickly. These results are essential for designing effective relief efforts for this crisis and for future natural disasters.